Injection pump for internal combustion engines



May 31, 1938. A. MEYER ET AL 2,119,472

INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES Filed Dec. 11, 1954 'UNITED STATES PATENT OFFICE.

INJECTION PUMP FOR. INTERNAL com- BUSTION enemas Alfred Meyer, Max Hurst, and Friedrich Wilhelm Stockmeyer, Stuttgart, Germany, assignors to Robert Bosch Gesellschaft mit beschriinkter Haftung, a corporation of Germany Application December 11, 1934, Serial No. 757,018 In Germany December 22, 1933 2 Claims.

The present invention relates to injection pumps for internal combustion engines.

The object of the invention is an injection pump, more particularly for multi-cylinder internal combustion engines, having a governor built on to the pump casing for controlling the amounts of fuel injected, the governing member of which adjusts itself to correspond to the pressure condition existing in the air suction pipe of the engine. In order to be able to keep the pressure surface, and thus the dimensions of the movable governing member and of the members exerting the return force comparatively small, it is important that the force whichis necessary for adjusting the members influencing the amount delivered by the pump should remain as far as possible uniform and small over the whole range of adjustment and under all working conditions.

According to the present invention, this requirement is fulfilled, and thus the premise for the employment of a sensitive governor obtained, by a pump being employed together with the governor, the adjusting rod of which acts on the members of each separate pump which control the amounts delivered, which adjusting members can always move with the same adjusting force free from back-pressure, independently of the delivery pressures obtaining and the delivery amounts for which they are adjusted. Such a pump is, for example, the well-known Bosch injection pump in which the amount injected is adjusted by the movements of a. controlling rod displaceably mounted in the pump casing and formed as a toothed rackbar, by the controlling rod simultaneously and similarly rotating through suitable intermediate members the pistons provided with oblique controlling surfaces of all theseparate pumps.

A high sensitivity of the governor, with the best utilization of the governing forces available, is produced, if in further carrying out the invention, the governor built on such a pump is constructed as a diaphragm governor, the diaphragm of which acts on the controlling rod of the pump as far as possible without the intervention of power-consuming intermediate members. By this means the friction and power losses unavoidable in piston governors due to leaky places in the piston guide are avoided. A chrometanned, stuifed leather, more especially goatskin or kid leather, has been found a very suitable material for the diaphragm.

An example of construction of the invention shown in the accompanying drawing, in which:-

Figure 1 shows, partly in elevation and partly in section, a four-cylinder injection pump having the governor built thereon.

Figure 2 is a section on the line A-B in Fig. '1.

Figure 3 is an elevation of the end of the 5 injection pump on which the governor is carried.

Figure 4 is a. section on the line C-D in Fig. 1, looked at in the direction of the arrow E.

Figure dis a diametral section through the governor diaphragm on a larger scale than the rest of the figures;

' In the casing a of the injection pump four separate pumps are arranged in a row, the pistons b of which are driven by a cam-shaft c. The fuel delivered by the pump pistons is injected through the outlets d and the injection nozzles (not shown) into the engine cylinders, which are also not shown. The amount of fuel delivered by the pumps can be altered in known manner by angularly turning the pistons b provided with an obliquely cut controlling surface.- This rotation is effected by means of a toothed rackbar e, which is common to all the pumps, and is slidably mounted in the pump casing. The rackbar engages in a pinion e associated with each separate pump and seated on a sleeve e. Each of the sleeves e" is inserted over the lower end' of a piston-guide bush, and is so connected by a claw-like clutch with a cross-piece b of the respective pump pistons b, that the piston can unimpededly perform its strokes relative to the sleeve, which is immovable in the axial direction, but cannot rotate relative to the revoluble sleeve.

' The shaft 0, which on its left-hand end projecting from the casing a carries a clutch half I which receives the drive, is mounted in ball-- bearings g, the outer races 71. of which are fitted in similarly formed annular extensions or flanges iof two bearing-covers k, k. The annular flanges suitably project into openings in'the casing 11. The diameter of the openings and extensions is so proportioned, that the shaft carrying the operating cams m for the pump pistons can be introduced from the side into the casing. Each of the two bearing-covers k, k is secured by screws which pass through its flange to one end of the pump casing..

The flange of the bearing-cover k is extended upwards, and carries, on its side turned away from the pump casing, an annular extension n, into the interior of which one end of the toothed rackbar e projects, and to which the pot-shaped governor casing 0 is fastened. Between the extension n and the governor casing o the outer edge of a diaphragm p isclamped, which is protected by a binding or border, shown in Figure 5. The diaphragm is composed of two discs 2 p of chrome-tanned, stufl'ed goatskin or kid leather secured together by an adhesive.

of the pin is secured to the right-hand end of the toothed rackbar e.

The vacuum chamber of the governor casing 0 has a place for connecting up a pipe t, which is connected to the air suction pipe i; of the engine behind a throttle-valve u, operable at will by the driver, so that in the interior of the governor casing the same vacuum always prevails as behind the throttle-valve in the suction pipe 0, This vacuum, which varies with the speed of the engine and the positionof the valve, tends to drawthe diaphragm p, together with the rackbar e linked thereto, towards the right into the stop position of the pump against thepressure of a return spring formed as a helical spring 10, arranged in the vacuum chamber.

In order, that the space enclosed by the diaphragm p, the annular extension n, and the supporting plate may be constantly connected with the outer air, holes H) are provided in the supporting plate, which are connected together by a. recess H on the side of the supporting plate bearing on the end face of the pump casing. The air current pulsating to and fro during the governing operation must take the devious path indicated by the arrows l2. The penetration of foreign bodies into'the chamber s is in this way rendered more dimculh.

The annular extension 11 is traversed by a rockshaft a: crossing at right angles to the axis of the diaphragm. One end of the shaft :2: projecting from the chamber carries a lever g, which can be operated by the driver through a suitable rod (not shown). Inside the chamber the rockshaft carries a finger-like lever a, which is shown in Figure 1 in its position of repose, in which it does not project into the path of the governing parts. On rocking the shaft the lever comes in contact with the end of the extension q of the diaphragm, and on being rocked further moves this, together with the rackbar coupled thereto towards the right against the force of the spring w until the delivery of the pumps is stoppedv and thus also the engine-is stopped. After releasing the lever y, a spring I5 coiled about the shaft rocks back the shaft, together with the lever z, into the position of repose shown in the drawing.

The fuel is supplied by a pipe I4 to the suction chamber l3 provided in the pump casing common to all the separate pumps.

Instead of the pump described which is a particularly' advantageous one, a different pump could also be employed, whose members which govern the amounts of fuel delivered can be adjusted without back-pressure and free from shock with a small force which remains substantiallythe same over the whole governing range.

-We declare that what we claim is:

1. An injection pump for an internal combustion engine comprising a pump casing, a plurality of pump members arranged side by side in said casing, a driving shaft for said pump members, an adjusting member mounted in said pump casing and arranged parallel with the driving shaft for varying the quantity of fuel delivered by said pump members, the resistance of said adjusting member to movement being substantially constant and independent of the quantity or pressure of the fuel delivered, a supporting plate secured on one end of said pump casing formed on its inner face as a bearing casing for said driving shaft and having on its outer face an integral annular extension, a governor casing secured to said annular extension and a diaphragm clamped between said annular extension and said governor casing, operatively connected with said adjusting member and displaceable in dependence upon the air pressure prevailing in the suction pipe of the engine to which the pump is fitted, the space between the diaphragm and said supporting plate being connected to atmosphere by means of a pair of openings in the supporting plate which are connected by a recess in the inner face of the supporting plate.

2. An injectionpump for an internal combustion engine comprising a pump casing, a plubers, an adjusting member mounted in said pump casing and arranged parallel with the driving shaft for varying the quantity of fuel delivered by said pump members, the resistance of said adjusting member to movement being substantially constant and independent of the quantity or pressure of the fuel delivered, a supporting plate secured on one end of said pump casing formed on its inner face as a bearing casing for said driving shaft and having on its outer face an integral annular extension, a governor casing secured to said annular extension, a governor member in said governor casing, operatively connected with said-adjusting member and displaceable in dependence upon the air pressure prevailing in the suction pipe of the engine to which the pump is fitted, a rock shaft extending transversely through said annular extension, means for rotating said rock shaft from a position of repose and a lever on said rock shaft within the casing adapted to engage said governor member on rotation of the rock shaft from its position of repose to cause displacement of the governor member and of the adjusting member in the direction for reduction of the quantity of fuel delivered by the pump.

ALFRED MEYER.

MAX HURST.

FRIEDRICH WILHELM STOCKMEYER. 

